Secondary electron emission tube



DeC.A 21, 194.8. vy SOLLER V Y 2,456,654

SECONDARY ELECTRON EMISSION TUBE ATTORNEY Dec'. 21, 1948.

w. soLLER SECONDARY LECTRON EMISSION TUBE '5 Sheets-Sheet 2 original Filed Aug. 19, 1943 :Plaza- Arran/V67 1N VEN TOR. Q/U,

Dec. 21, 1948. w. sQLLl-:R 2,456,654

V SECONDARY ELECTRON EMISSION TUBE Y original Filed Aug. 19, 1945 s sheets-sheet 3 aaa/a,

Patented Dec. 21, 1948 l 2,456,654 SECONDARY ELECTRON EMISSION TUBE Walter Soller, Cincinnati, Ohio, assigner of onehali' to William H. Woodin, Jr., San Mateo,

Calif.

Original application August 19, 1943, Serial No. 499,260. Divided and this application August 29, 1944, Serial No. 551,689

6 Claims. (Cl. 25o-27) My invention relates broadly to electron tubes and more particularly to a deiiection type of secondary electron emission tube for wide application in the electronic industry.

This application is a division of my application Serial No. 499,260, filed August 19, 1943, for Electron tube.

One of the objects of my invention is to provide a construction oi deflection type secondary electron emission tube having associated input and output circuits wherein substantially complete isolation of the input fromv the output circuit is eiected.

Another object of my invention is to provide a construction of secondary emission tube having means for directing a shaped beam of electrons against an electrode assembly of the secondary electron emission type.

Still another object oi my invention is to provide an arrangement of magnetically controlled beam tube having means for directing a shaped beam of electrons against an electrode assembly of the secondary electron emission type.

A further object oi my invention is to provide a magnetically controlled beam tube of the regenerative type for increasing the magnitude of the electron current through the beam tube.

Other and further objects of my invention reside in the construction and arrangement oi the elements of deection type secondary electron emission tubes as set forth more fully in the speciilcation hereinafter following by reference to the accompanying drawings, in which:

Figure 1 is a schematic longitudinal sectional view oi' the secondary emission tube oi my invention; Fig. 2 is a transverse sectional view oi the tube taken substantially on line 2-2 of Fig. 1; Fig. 3 is a longitudinal sectional view taken on line 3-3 of Fig. 1; Fig. 4 is a schematic circuit arrangement ofthe magnetic control system for the secondary emission tube showing the regenerative circuit arrangement employed with the tube and the arrangement of secondary emission electrodes in transverse section; Fig. is a sectional view taken substantially on line 5-5 oi Fig. 4; Fig. 6 is a sectional view taken substantially on line 5--5 of Fig. 4; Fig. '7 is a schematic circuit arrangement of the beam tube of my invention connected in a direct current amplication circuit; and Fig. 8 is a schematic circuit arrangement showing the beam tube of my invention arranged in a magnetically controlled regenerative direct current amplication system.

In Figs. 1-3 I have illustrated an electron beam tube i of high sensitivity in which a flat electron beam of rectangular section normally passes directlythrough a rectangular aperture H1 in secondary electron emission plate IIB for zero input. The electron beam generator is illustrated as including the electron emitter repre- 2 sented generally at 20, the beam forming plates being shown at 3|32 and 33 entirely surroundlng the emitter with slots 3|a, 32a and 33a in the beam forming plates registering one with the other for shaping the rectangular electronic beam. That is to say, the beam forming plates are shown at 3i, 32 and 33, each including transversely extending slots indicated at 3|a, 32a and 33a. A rectangular narrow .beam is thus projected between the deflection plates 1 and 8 to bombard the secondary emission plate system.

It will be observed that a steady potential is maintained between the cathode and'the beam forming plate 3l as represented at 34 in Fig. 2. The positive terminal of the direct current source 34 connects to the cathode 20 while the negative terminal of direct current source 34 connects to beam forming plate 3|. A direct current source 35 is provided with its negative terminal connected to beam forming plate 3l and its positive terminal connected to beam forming plate 32. A direct current source 35 is provided with its negative terminal connected to beam forming plate 32 and its positive terminal connected to beam forming plate 33. The circuit is completed from the positive terminal of direct current source 36 to the auxiliary plates 53 and 54 connected together and connected to the positive terminal of direct current source 36.

The auxiliary plate system is formed and shaped to eliminate sharp edges wherever a concentration of fleld strength exists. By shaping the auxiliary plates in elliptical section and provlding coactng pairs of plates as represented at 8|, 32, 53 and Bt. the eld strength around the plate system is rendered uniform and excessive concentrations of field strength are eliminated. As a further precautionary measure for reducing edge effects and erratic electron discharges, the plate member is rounded at its edges. The auxiliary plates 53 and 64 also serve to shield the electron beam from any possible transverse field across collector plates 6I and 52. This form of tube is highly practical for use in all of the various circuit arrangements heretofore employing conventional control grid tubes with the added advantage that reactionary eflects between the control system and the output circuit are substantially eliminated. 1

That part of the electron beam that does not strike the plate element H6 will pass through the grid electrode 54 and strike plate electrode 55 which is specially related to grid electrode 54. The secondary electron emission from plate electrode 55 is prevented from reaching auxiliary plates 5I, 62, 53 and 6I by the negative potential impressed upon grid electrode 54 from potential source 51. In order to further reduce the possibility of secondary electrons discharging from plate electrode 55 and being collected by auxiliary electrodes 62, 60 and 84, the plate 55 is constructed from a material which does not readily emit secondary electrons while plate member ||5 is coated for the particular purpose of producing high secondary electron emission properties. A slight deflection of the beam produced by a small input between plates 1-8 with this construction will cause a relatively large portion of the beam to strike plate ||6 causing a correspondingly large secondary emission from it; This greater sensitivity is caused by a large change in secondary emission produced by a slight change Yin the deflection of the beam. Potential source 31 is connected between the electron beam generator G and the secondary emission plate ||5 and plate member 55 placing positive potential on the plate system and negative potential on the electron generator. A potential source 5B is connected between plate member 55 and auxiliary plates 5|-62 through output resistor 59 leading to output circuit 4|.

In Figs. 4, 5 and 6 I have shown a construction of tube in which a -magnetic control system is employed for deflecting the beam. 'I'he magnetic control system is a coil structure |20 of magnetic alloy having pole pieces ||8 and ||9 terminating in a magnetic gap |2| through which an electron beam from electron beam generator G of the type heretofore explained is propagated. The

magnetic control system operates to control the displacement of the electron beam. The magnetic alloy core concentrates the magnetic field to substantially the thickness of the electron beam irrespective of the size of the control windings at the gap where the magnetic circuit passes through the beam as shown more clearly in Fig. 5. The magnetic control system includes an input winding |23 connected to input circuit terminals 40 ,and a regenerative winding |24 which connects to the anode system as shown.

With the construction of core 20 asshown,

onthe core either positive or negative feedback. even on D. C. operation, is obtained. Very small D. C. voltages can be amplified with this arrangeseveral coils can be caused to affect the magnetic v field and so better facilitate feedback and balancing arrangements with deflection beam tubes. In this circuit alternating current signal energy is employed. The y output transformer |25 is arranged so that the current produced in an additional secondary coil |28 can be fed back into the independent coil |24 from that through which the input current passes. Winding |24 is wound on the core |20 of the magnetic deflecting unit. By this means an entirely independent positive or negative feedback can be obtained. The positive feedback will give greater amplification than can be produced without the feedback, while the lnegative feedback will produce stability of operation of the tube and circuit. Resistance' |3| is provided in circuit between control winding |24 and secondary coil |28 to adjust the phase of the feedback to synchronize with the deflection of the beam. The output from the cathode system 8|52 and plate electrodes 5|-55 is supplied to primary winding |26 by transformer |25 by which a portion of the energy is transferred through windingv |28 to the magnetic control winding |24. Secondary winding |21 leads to the output circuit designated at 4|.

Fig. 7 shows a tube that is similar to the tube of Figs. 4-6 except that it allows the feedback feature to be accomplished for D. C. current.

The current in the output circuit is fed directly back through the second coil |24 of the magnetic dellecting unit through phase resistor |'3|. By using suitable connections and by the relative direction of the winding of the two coils 23|24 ment and the higher sensitivity and stability oi' positive and negative feedback systems can be obtained There is a decided advantage in this independence of feedback in these deflection amplifying tube systems. I'his circuit is adapted to thermocouple and thermopile voltage amplication as it is a voltage sensitive D. C. amplifier.

The shield |29 around the tube is of high permeability material so that external electric and magnetic fields will not disturb the operation of the tube. .As both shield |28 and core |20 are of high permeability material and the core 20 is entirely inside and away from the "shield, thev magnetic field will remain in the core direct current amplifier 13 has the grid cathode -circuit thereof connected to the resistance 59 in the output circuit 4| of the anode system of the deflection tube. Tube 13 includes cathode 13a, control grid 13b and anode 13c arranged as shown. The cathode is supplied with power from power source |30 through resistors 15 and 16. The output resistance 59 in series with potential source 58 in the output circuit of the electron beam tube connects to control grid 13b and cathode 13a through resistance 15. `The output circuit of tube 13 connects from anode 13e through resistance 11 and to the potential source |30 as shown.

The output current of this amplifier isfed back into the second coil |24 on the magnetic deflection core |20 through phase adjusting resistor |3l. The operation of the tube of Fig. 8 is similar to that shown in Fig. 7, and when negative feedback is used, even greater stability is accomplished than with that of circuit in Fig. 7. Fig. 8 is not restricted to the application of the invention to one amplifier stage but any number of stages of amplifiers and the current in the last stage is fed back into the second coil |24 of the magnetic core. The larger the amplificais positive feedback, this arrangement will give even greater amplification. The tube of Fig. 8 employes the principle of controlled emission in the output part of the tube in which feedback is employed.

While I have described my invention in certain preferred embodiments, I realize that modifications may be made in the arrangement and method employed and I desire that it be understood that no limitations upon my invention are intended other than may be imposed by the scope of the appended claims.

What I claim and desire and desire to secure by Letters Patent of the United States is as follows:

1. An electron discharge system comprising an electron discharge device for propagating an electron beam, means for shaping said beam into substantially rectangular section, means for controlling the angular sweep of said electron beam, a plate system disposed in the path of said electron beam comprising a plate electrode containing aus-asu a substantially rectangular slot for the passage of said electron beam in central position a secondary. electron emitting coating carried by said plate electrode throughout the area surrounding the slot therein, a grid electrode disposed rearwardly of said plate electrode and maintained at negative potential with respect to the aforesaid plate electrode, a plate electrode disposed behind the aforesaid grid electrode and maintained at positive potential with respect to said grid electrode, secondary electron collecting plates disposed adjacent said first mentioned plate electrode, an output circuit including said secondary electron collecting plates and said plate system and activated whenever said electron beam is diverted from a central position passing through the slot in said plate electrode.

2. An electron tube system comprising an electron generator for generating and propagating a beam of electrons, means for shaping said beam into a narrow substantially rectangular section a plate system disposed in the path of said beam of electrons, said plate system including a secondary electron emitting plate member and an associated secondary electron collecting plate member, said plate member being centrally slotted in substantially rectangular section corresponding to the section of said beam and having a secondary electron emitting coating surrounding the central slot therein, a grid electrode disposed between said plate members and charged negatively with respect thereto, an output circuit interconnecting said plate members, a magnetic control device including a magnetic core terminating in a, magnetic gap on opposite sides of the normal path of said beam of electrons, an input winding on said magnetic core for electro-magnetically controlling the magnetic circuit through the magnetic gap in said magnetic core, and an auxiliary winding on said magnetic core connected with said output circuit for regeneratively controlling the current therein for effecting angular displacement of said beam from the slot in said plate member to the secondary electron emitting coating thereon.

3. An electron tube system comprising an electron beam generator for generating and propagating an electron beam, means for shaping said beam into a substantially rectangular section a plates/ystem disposed in the path of said electron beam, said plate system including a secondary electron emitting element and a secondary electron collecting element, said secondary electron emitting element having a central substantially rectangular slot therein conforming in shape to the section of said beam, a grid electrode disposed between said elements and charged negatively with respect thereto, an output circuit interconnecting said elements, input means for controlling the scanning of said plate system by said electron beam, and means regeneratively coupling said output circuit with said input means for regeneratively acting upon current delivered to said input means.

4. An electron tube system comprising an electron beam generator for generating and propagating an electron. beam, means for shaping said beam into a substantially rectangular section a plate system including a secondary electron emitting element disposed in the path of said electron beam and a secondary electron collecting element, said secondary electron emitting element having a central substantially rectangular slot therein conforming in shape to the section of said beam,

a grid electrode disposed between said elements.

and charged negatively with respect thereto, an output circuit interconnecting said elements, a three electrode tube system including grid, cathode and anode electrodes, connections between said output circuit and said -grid and cathode electrodes, an output circuit interconnecting said anode and cathode electrodes, and means for shifting said electron beam for scanning said secondary electron emitting element in the area surrounding the central slot therein for producing current changes in the circuits associated with said grid, cathode and plate electrodes proportional to current changes impressed upon said means,

5. An electron beam tube comprising an electron generator, means for shaping propagated electrons into a substantially rectangular beam, a plate electrode disposed in the path of said beam and having a substantially rectangular slot therein for the normal passage of said beam, a secondary electron emitting coating formed on said plate electrode surrounding the slot therein, an electron collecting plate electrode disposed behind the slot in the aforesaid plate electrode, a. grid electrode disposed between said plate electrodes and charged negatively with respect thereto, secondary electron collecting plates adjacent said first mentioned plate electrode, and means i'or angularly displacing said substantially rectangular beam from a substantially central position passing through the rectangular slot in said iirst mentioned plate electrode to a position striking the secondary electron emitting coating on said first mentioned plate electrode throughout the area surrounding said substantially rectangular slot for liberating electrons for collection by said secondary electron collecting plates.

6. An electron tube system comprising an electron discharge device for propagating an electron beam, means for shaping said beam ln substantially rectangular` section, means for controlling the angular sweep of the electron beam, a plate system disposed in the path of said electron beam comprising a pair of spacially disposed plates, one of said plates having a substantially rectangular plot disposed centrally therein conforming in shape with the shape of said electron beam, a, secondary electron emitting coating on said plate system surrounding the central slot therein and the other of said plates being disposed behind the slot in the aforesaid plate, a grid electrode arrangement between said plates and charged negatively with respect thereto, and a plurality of secondary electron collecting plates disposed adjacent said plate system and out of ,the path of sweep of said electron beam, said secondary electron collecting plates each being elliptical in section and coextensive with the length of said plate system.

WALTER SOLLER.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,506 Soller Sept. 14, 1937 2,068,040 Schaberle Jan. 19, 193'1 2,096,653 Soller Oct. 19, 1937 2,190,069 Hollmann Feb. 13, 1940 2,276,758 Brueche et al Mar. 1'7, 1942 2,305,646 Thomas Dec. 22, 1942 2,357,922 Ziebolz et al Sept. 12, 1944 2,369,206 Barnes Feb. 13. 1945 

